Laser welding of tailored blanks made of Al-Si-coated 22MnB5 steel using a filler wire and a variable energy distribution laser optics

Abstract

Laser welding of Al-Si coated steels for hot stamping in automotive applications is problematic due to the mixing of the coating layers inside the molten pool that weakens the resulting weld seam. The most common welding procedure used in this case consists in removing the Al-Si layer through laser ablation prior to the joining. Although in-situ ablation of the Al-Si coating can be costly and time consuming, this method continues to be the most widely used by major producers of tailor welded blanks (TWB). In this work, a novel approach consisting in joining as-received (i.e. not decoated) materials using a filler wire and an innovative variable energy distribution (VED) laser optics is introduced and tested on TWB made of 22MnB5. Specimens obtained from a 33 full factorial design of experiment have shown a mechanical resistance much higher than that observed in as-received welded then hot stamped cases. SEM and hardness analyses have been performed to better investigate the quality of the resulting weld seam. Variations of the main process parameters have been considered on an iso-thickness and iso-material configuration, empirically demonstrating the stability and reliability of the proposed methodology as well as its suitability for production purposes.